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(No Model.) w 2 Sheets--Sheet 1.

S. NICHOLSON. .GRINDING MACHINE.

No. 556,638. Patented Mar. 17, 1896.

witnesses. '7 HNVENW R.

' (No Model.) 2 Sheets-Sheet 2.

S. NICHOLSON. GRINDING MACHINE.

No. 556,638. Patented Mar. 17,1896.

UNITED STATES PATENT OFFICE.

STEPHEN NICHOLSON, OF PROVIDENCE, RHODE ISLAND.

GRINDING-MACHINE.

SPECIFICATION forming part of Letters Patent No. 556,638, dated March 1'7, 1896.

Application filed May 19, 1894. Serial No. 511,869. (No model.)

To aZZ whom it may concern.-

Be it known that I, STEPHEN N IOHOLSON, of Providence, in the county of Providence and State of Rhode Island, have invented a new and useful Improvement in. Grinding-Machines, of which the following is a specification, reference being had to the accompanying drawings, in which Figure 1 shows a vertical central section of the preferred form of my machine as a whole. Fig. 2 is a plan partly in section on line 2 2 of Fig. 1, showing the relative centers of rotation of the grindstone and work. Figs. 3 and i showa modification, Fig. 3 being an enlarged sectional view of a portion of the workframe, a work-holder and a guide. Fig. at is a cross-section on line 4 4 of Fig. 8 to show the position of a guide-lip. Fig. 5 shows a modification of the work-holder and its guide provided with a brace or steady-plate. Fig. 6 shows another modification of the work-holder in which the work is held angularly and the work-holder left open at the bottom.

My invention relates to improvements in grinding machinery in which the work (chisels,cutter-blades,files, straight-edges, squares and other tools or mechanical implements) while being ground is held in suitable fixtures attached to the machine; and the objects of my invention are, first, to so hold the articles to be ground as to wear the surface of the grindstone uniformly; secondly, to secure permanency of the working-lines of the machine by removing working parts of the machine away from the flow of grit, and, thirdly, to secure economy of operators time by reducing labor to the mere handling necessary to place the articles to be ground in the machine and to remove them.

In the drawings illustrating on the whole the preferred of the several embodiments of my invent-ion now contemplated by me the base B, uprights U U and cross-tie F form the frame of the machine. The main shaft T passes through the tie F, which forms an upper bearing for shaft T, while its lower end runs in the bearing-box L attached to base B. Toward the lower end of the shaft are two flanges which clasp the stone S. At the top of shaft T is located the pulley I, which receives its power and motion from a suitablydriven belt and causes the shaft and stone to rotate.

The cross-tie F is provided with a projection F, formed into a circular disk whose center 0 is placed at one side of the shaft T. In Fig. 2 this center 0 is represented by a dot 0. Upon this projection F revolves and rests the work-frame D carrying the several workholders A A supported on guides R R, upon which they are movable. In the drawings two work-holders and guides are shown. In practice the number of such holders and guides may be increased or diminished. By allowing the work-holders to drop the work 0 (see Fig. 1) is brought into contact with the revolving stone S and so remains until sufficient grinding has taken place, when the holder is lifted and the work changed and the operation repeated.

If the work were to remain in one position, it would tend to wear the stone at the points of contact only and would soon produce a groove in the stone.

The frame and work are revolved from time to time upon the projection F, which, being located eccentrically to the center of revolution of the stone S,will cause the work to change its position on the stone and traverse to the inner and then to the outer edge and back again on each revolution of the frame. By making the eccentricity of the disk rim equal to the width of grindstoneface S S one revolution of the work-frame D will cause the work to traverse the entire width of the working face of the stone, thus bringing all portions of the stone into contact with the work, and if the work-frame be made to revolve at a constant speed the wear will be practically uniform and the surface of the stone kept true.

To secure a constant movement of the workframe, a rim-gear E is driven from pinion II, which in turn is driven through shaft I and gear J by pinion-gear K attached to shaft T, or it is practical to substitute in place of rimgear E a grooved pulley or any other suitable means for transferring motion; but if desired the mechanism for turning the work-frame may be dispensed with and the frame turned by hand.

The work 0 is held in work-holders A A,

the lower portions of which are of any desired form necessary to receive and hold the work to be ground. In the drawings I show flat-faced pieces of work 0, the edges of which it is desired to grind fiat. By forming the work-receiving grooves or recesses in the work-holder at an angle the edges may be ground on any desired bevel instead of being ground flat, as will be plain without more particular description.

The work-holders are supported 011 guides R R, which are angular in crosssection and have their upper ends formed into a lip, which, when the work-holder is raised, engage the latches N N to hold the holders A in suspension while changing the work.

I have shown the ends of the work-holders A closed to prevent grit and dirt from coming in contact with the bearing surfaces of guides R.

In cases where the work to be ground requires considerable pressure the friction is liable to cause heat. To overcome this (especially when grinding hardened steel) I introduce a jet of lubricant or water through the pipe 7, (shown in Fig. 1,) which jet I cause to strike the stone near its center, from which it is distributed to the outer edge and thrown off by centrifugal force, thereby nicely and evenly lubricating the face of the stone. By this same means I cause loose grit, mud or emery or grinding or polishing material to be supplied as well as water or lubricant, and with marked economy and efficiency as small quantities only are necessary owing to the perfectly uniform distribution obtained by this centrifugal force.

I do not confine my invention to a machine for using grindstones, but by grindstone or stone wherever used I mean emerywheels, laps or any other form of abrasive wheel, plate or disk.

In Figs. 3 and l, showing a modification of the work-holder and guides, I have arranged the machine with round guides screwed or fastened to the frame D, as shown in Fig. 3. This permits the work-holder to be revolved upon the guide to secure a more convenient position for removing and replacing some varieties of work. In this case the top of the work-holder A is formed into a rim, Fig. 3, and the latch N replaced by a stand N, which has a projection Gr. The rim is slotted at A to receive projection G, and this prevents the work-holder from turning in either direction when down and when the work is in contact with the stone. When, however, the workholder is elevated and the rim is above the top of the projection G, the work-holder can be revolved without falling, the rim resting upon G at all positions excepting when the slot in the rim and the projection G correspond.

In Fig. 5, showing another modification, the guide R passes through the work-holder A, which is adapted to grasp the work on its side, the guide B being connected with the steady-plate R, which extends to another guide R. This construction is desirable for heavy work, as work ends of the guides R are thereby braced.

In Fig. 6 I show a modification for the purpose of fully illustrating how the work may be held to be ground at a bevel.

IVhat I claim is- 1. In a grinding-machine, an abrasive wheel in combination with a work-carrying frame, having a work-holder movable from and toward the wheel and formed to grasp and carry a tool to be ground, the frame rotating in a circle, whose center of motion is eccentric to that of the abrasive wheel, substantially as described.

2. In a grinding-machine, the combination of an abrasive wheel with a base, suitable supports and a cross-tie having a projection formed with a circular flange eccentric to the center of the abrasive wheel; a work-carrying frame mounted on said flanged projection, and a work-holder, all substantially as and for the purpose set forth.

3. In a grinding-machine, an abrasive wheel in combination with an eccentrieally-rotating work-carrying frame having a work-holder, movable from and toward the wheel and formed to grasp and carry a tool to be ground, the work-carrying frame having a projecting guide 011 which the work-holder slides, substantially as and for the purpose set forth.

4. In a grinding-machine, a work-carrying frame in combination with an abrasive wheel, the work-carrying frame having an extension, with a work-holder formed to grasp and carry a tool and movable on the extension from and toward the wheel; and means for locking the movable work-holder at a distance from the stone, substantially as and for the purpose set forth.

STEPHEN NICHOLSON.

Witnesses:

EDWARD S. BEACH, A. I. CRAWFORD. 

